This invention relates to a mechanism for controlling the vertical position of a trailer floor having a pivoting air spring suspension system such that the trailer floor maintains a relatively fixed vertical position level to an adjacent dock when parked for loading or unloading.
During the transport of goods by heavy tractor/trailer vehicles it is necessary for the trailer to maintain a relatively smooth and uniform position during travel over uneven road surfaces. This is generally accomplished by the incorporation of an air ride suspension system that allows for a range of movement between the trailer and the rotating wheels such that the trailer may be protected from a degree of shock imparted to the rotating wheels that are directly exposed to the road surface.
An air ride suspension system typically utilizes a pivoting air spring system to connect the wheels to the trailer. A wheel axle is contained along its length by an axle housing which is attached to the trailer floor at an area above the axle housing by way of an air spring system. The axle housing further is pivotally attached to a frame bracket extending downward from the trailer floor, typically by way of a pair of parallel elongate upper and lower control arms. The angular position of the pivotally attached control arms varies with respect to the generally horizontal trailer floor during transport of the trailer.
While the pivoting spring system reduces the degree of shock imparted to the trailer during transport, it serves as a hindrance when the trailer is parked at a dock during loading and unloading of goods as the pivoting air spring suspension system is unable to maintain a desired trailer floor height. When parked at a dock, the trailer floor height will fluctuate up and down as a lift truck drives on or off the trailer causing load force changes into the suspension system.
A height control system cannot react efficiently enough to add or exhaust air from the air springs to maintain a constant trailer floor height. This would result in a variable dock board ramp angle. At worst, a trailer may be parked having a depleted air reserve thus leaving the suspension system in the full jounce position. This would, in some cases, cause ramp angles steep enough such that the lift truck cannot negotiate the dock board on or off of the trailer.
It would be desirable to provide the trailer with a mechanism that allows the pivoting components of the pivoting air spring suspension system to be locked or fixed at variable levels so that when parked, the trailer floor may be at a desired elevation as the adjacent loading dock surface during loading or unloading of goods. Thus, a variable dock board ramp angle would be eliminated, as the suspension system would not be in a position to fluctuate in response to varying lift truck loads.
In a series of disclosed embodiments of this invention, a trailer is optimally positioned at an adjacent loading dock by way of an air height control system such that respective adjacent floor surfaces are held at a desirable elevation level and the trailer parking brakes are then set. With this accomplished, an inventive mechanism is introduced that can incrementally fix or lock the angular position of the pivoting components of the pivoting air spring suspension system thereby fixing the trailer floor elevation while parked at an adjacent loading dock.
In a first embodiment of the inventive locking mechanism, the pivoting suspension system components, which may comprise a pair of parallel elongate upper and lower control arms extending from the wheel axle housing to the trailer floor frame bracket, are provided with an adjustable length diagonal support that is pivotally attached at one end to the trailer floor frame bracket. The distal end of the adjustable length diagonal support may then be fixed into one of a plurality of locking positions by way of a stop device positioned on the wheel axle housing that has a plurality of incrementally spaced fixed rest surfaces.
In a second embodiment of the inventive locking mechanism, the pivoting suspension system components are provided with an elongate diagonal support arm pivotally attached at one end to the trailer floor frame bracket. The distal end of the diagonal support arm has a cam profile that is configured to make contact with and rest against the wheel axle in a plurality of rest positions thus fixing the angular rotation of the pivoting suspension system components.
In a third embodiment of the inventive locking mechanism, hydraulically activated telescoping stands are provided. These stands extend downward from the trailer floor to the ground in a plurality of stop positions such that the angular rotation of the pivoting suspension components may be resisted.
In a fourth embodiment of the inventive locking mechanism, the pivoting suspension components are provided with activated locking collars at each pivotal connection to the trailer floor frame bracket. The locking collars enable a plurality of stop positions thus fixing the angular rotation of the pivoting suspension components.
In a fifth embodiment of the inventive locking mechanism, piezo electric pads are positioned on a surface of the trailer floor frame bracket. The pivoting ends of the pivoting suspension components, or parallel upper and lower control arms, that are pivotally connected to the trailer floor frame bracket are provided with a plurality of small extensions. When energized, the piezo electric pads would trap and immobilize at least one extension thus fixing the angular rotation of the pivoting suspension components.
These and other features of the present invention can be understood from the following specification and drawings, the following of which is a brief description.